The present invention relates to a linear switch with high off-state isolation for use in, for example, video waveform monitors, personal computers and/or graphic encoders.
In the prior art, in order to provide linear switching, two 4-quadrant multipliers and a semi-amplifier are needed to implement a linear switch It is generally not possible to achieve high off-state isolation, so that additional non-linear (full-on/full-off) switches are employed to block each signal source when faded to its lowest feedthrough level (off-state). It would be desirable to provide for high isolation capability without the need for additional cut-off switches (such as required in the prior art) which will greatly reduce circuit complexity.
In addition, it would be desirable to provide a linear switch that can be utilized in serving both low end and high end applications (e.g., consumer grade VTR equipment as well as television video signals).